Since the '80's engine specific. Aerospace machinist prior.

Funny thing about that timing. depending on how you intended to run our timing curves pretty much suck. Especially since they really aren't "curves" They start from 5 degrees or so at zero and sharply ramp up at about 3,000 rpm to 28 and stay there. There is no alteration in the advance after it ramps up, just steady at 28 to 30* depending on how accurate the chip is. The only true "curve" on cdi ignitions was with the mechanical advance, which was why they had a so much smoother mid range.

For those that desire to debate the point and rpm values previously noted, I was deliberately noting values that were not completely accurate. I'm prohibited from noting the specifics.